201008067 六、發明說明： 【發明所屬之技術領域】 本發明一般係關於波長轉換裝置以及該裝置之製造方 法。更特別地，本發明-些實施例侧於波長轉換裝置以 及其製造方法，其使祕化週期操作喊少布拉格共振以 及相關光線向後反射，同時保持波長轉換裝置之有效轉換 效率。 - 【先前技術】 - 包含週期性極化非線性光學材料例如銳酸鋰之波長轉 換裝置可配置成使雷射承受輸人訊號頻率加倍，其經由使 用非線性光學材料内週期地倒置的範圍藉由採用準相匹 配達成。不過，這些週期地倒置的範圍會在極化非線性光 學材料之相位相匹配波長下產生不想要的布拉格共振（即， 在輸入訊號波長下波長轉換裝置使輸入訊號之頻率以最大 效率加倍)，其促使由波長轉換裝置至雷射之不想要向後反 〇 射，其會負面地影響雷射之穩定性於當反射發生於基本波 長中。額外地，假如布拉格共振發生在頻率加倍的波長内， . 布拉格共振能夠會促使發射功率顯著地下降。本發明之實 施例藉由操作週期地極化非線性光學材料之極化週期減少 向後反射至雷射以破壞極化領域導致之布拉格共振，因而 提高雷射之穩定性。 【發明内容】 依據本發明一項實施例，提供製造波長轉換裝置之方 法，該裝置包含非線性光學材料，具有輸入面，輸出面以及 201008067 波導區域由輸入面延伸至輸出面。依據該方法，波長轉換 f置藉由_波長職裝置之她她配波長^以及決 疋出波長轉換裝置之相位相匹配波長理想的極化週 期而製造丨。麵性光學材·由引發波導區域為依 ^地疋位之領域加以極化，其包含不規則地變化領域寬度， f寬度由理想的極化週期Λ f加上錢去分紐界定出，使 得布拉格共振以及相職由不制地變化領域寬度極化之 ❻波，轉換裝置發出至雷射之光線的向後反射至少小於一個 -數量級布拉格共振以及以理想的極化週期Λι極化之非線 性光學材料_後反射。不規則地變化領域寬度由波 長轉換裝置極化之輸人碱_換效率至少為最大轉換效 率之一半。 依據依據本發明另-實施例，提供製造波長轉換裝置 之方法，該裝置由非線性光學材料構成，具有輸入面，輸出 面以及波導區域由輸人面延伸讀出面。依據該方法，波 ⑩長轉換裝置藉由辨識波長轉換裝置之相位相匹配波長^ 以及決定出波長轉換裝置之相位相匹配波長h的理想極 •化週期Λ,而製造出。非線性光學材料藉由引發波導區域 為多個依序地定位之領域加以極化其包含多個理想的極 化領域以及一個或多個非—理想的極化領域其中非理想 的極化領域包含由理想的極化週期八!加上或減去不連^ 值界疋出威以及理想的極化領域包含理想的極化週期 〜界定出之寬度。選擇不連續值，使得由第二—半波導區 域反射光線之相位與第-一半波導區域反射之光線的相位 201008067 相反以由波長轉換裝置極化具有非—理想極化領域之輸入 訊號的轉換效率至少為最大轉換效率之一半。 依據依據本發明另一實施例，提供波長轉換裝置。更 特別地，依據本發明之實施例，波長轉換裝置包含非線性光 學材料，具有輸入面，輸出面以及由輸入面延伸至輸出面之 波導區域。波導區域更進一步包含多個依序地定位之領域 ，其具有由理想的極化週期Λ,加上或減去分裂值界定出之 〇 不規則地變化領域之寬度。小於理想的極化週期八,之分 - 裂值使得布拉格共振以及相對應光線之向後反射大小至少 小於在理想的極化週期人!被非線性光學材料極化光線之 布拉格反射。分裂值亦使得具有不規則地變化領域寬度之 輸入訊號被波長轉換裝置轉換的效率至少為以理想的極化 週期Λι極化之非線性光學材料的最大效率一半。 依據依據本發明另一實施例，提供波長轉換裝置，其包 含非線性光學材料，具有輸入面，輸出面以及由輸入面延伸 〇 至輸出面之波導區域。更特別地，依據一項實施例之波導 &域包含多個理想的極化領域以及一個或多個非-理想的 . 極化領域。非-理想的極化領域包含由理想的極化週期ΛΙ 加上或減去不連續值界定出之寬度，其小於理想的極化週 期ΛI，以及理想的極化領域包含由理想的極化週期八,界 定出之寬度。 【實施方式】 本發明一般係關於半導體雷射以及波長轉換裝置，例 如第二諧波產生晶體(SHG)，其可以不同方式加以配置。例 5 201008067 如以及藉由列舉性及非限制性地，短波長光源能夠配置成 作為高速調變，其藉由將單一波長半導體雷射，例如分散回 授(DFB)雷射，分散佈拉格反射器（j)BR)雷射，垂直腔表面_ 發射雷射(VCSEL)，垂直外部空腔表面-發射雷射(vecsEL) 或法布立-培絡雷射與光線波長轉換裝置例如SHG晶體合併 而達成。 如熟悉雷射設計之人們了解，DFB雷射為共振-腔雷射， ❹ 其使用方格或蝕刻至半導體材料作為反射性媒體類似的結 - 構。⑽R雷射為钮刻布拉格光栅實際地由半導體雷射電子 泵運面積分離之雷射。另一方面，法布立-培絡雷射並無波 長選擇性區段以及，因而產生多種波長。為了操作法布立— 培絡雷射為單模狀態，其因而必需加入波長選擇性分量至 光學路徑以反射一些光線朝向二極體以及使波長穩定。該 功月b此夠藉由在SHG晶體波導部份内對布拉格光拇積分達 成。已考慮依據本發明使用這些以及其他型式雷射。 ❹ 波長轉換裝置可包含SHG晶體。雖然SHG晶體產生輸出 訊號，其具有頻率為原始或輸入光學訊號之頻率兩倍，這些 _ 訊號變成彼此為異相。當光線運行於波導區域時，基本（即 ，輸入）以及第二-諧波波長下之光線變為異相的，使得產生 接近於波長轉換裝置之輸入面處第二-諧波訊號與產生接 近於波長轉換裝置輸出面處第二-諧波光線訊號為異相。 此導致產生非常少量第二-諧波光線。為了得到波長轉換 裝置中產生的第二-諧波光線訊號間之建設性相位相匹配 ，採用準-相位相匹配。準-相位相匹配可藉由週期地倒置 201008067 的極化領域於雜性材叙波導_内而達成 。極化包含 週，月地倒置波長轉換裝置晶軸之方位以確保紅外線以及可 見光兩者’。魏長键裝置讀賴乎鋪職。藉由加 入相位偏移於每—領域處可最終相位改正 。適合作 為SHG曰曰體之非線性光學材料可包含非限制性之週期性極 化銳酸經(PPU)，獅地極化錄賴(ppLT)，以及週期地 極化卸氧欽基磷酸鹽⑽TP)。極化可可藉由許多處理過 ❹程導入波長轉換裝置，包含例如電子光束掃猫，施加電場， . 或晶體成長。 波長轉換裝置可藉由調整例如膽簡DBR或腦雷射 至波長轉換裝置之頻譜中央而產生基本雷射訊號之較高諧 波，其轉變波長至530nm。不過，在該較高諧波產生系統中， 重要參數為波長雷射之穩定性二極體。例如摻雜Mg〇 ppLN 之波長轉換裝置的波長轉換效率強烈地決定於雷射二極體 以及波長轉換裝置間之波長相匹配。波長轉換裝置之轉換 ⑩效率為波長非常狹窄之函數，使得任何波長不穩定產生頻 率加倍光線的強度波動。 我們已瞭解由波長轉換裝置之向後反射以及再注入至 半導體雷射對波長穩定性拌演關鍵性之角色。雷射例如dbr 雷射對回授非常靈敏性以及回授值低至-60至_7〇dB時會使 波長變為不穩定。例如，布拉格光栅可導致雷射系統中向 後反射。我們亦已瞭解，雖然波長轉換裝置例如週期地極 化SHG晶體無法刻意地包含誘導布拉格光栅於])职或dfb雷 射系統中，大塊SHG晶體存在一些週期性或接近地週期性特 201008067 性例如晶體極化或其他晶體波導形成相關之特性。這些特 性作用類似於不想要布拉格光栅以及產生顯著的回授至雷 射二極體。這些布拉格反射會產生雷射不穩定性於發生在 基本波長下時及/或功率下降於其發生在頻率加倍的波長 下時。 對於在發展半導體雷射光源中波長相匹配以及穩定性 相關之挑戰，本發明實施例係關於波長轉換装置以及其製 法以使由波長觀裝置之向後反射至轉體雷射減為 - 农低’因而提尚半導體雷射波長穩定性。雖然本發明概念 主要對雷射内容說明，已考慮在此所說明之控制方式亦使 用於各種型式半導體雷射中，包含非限制性之Dfb雷射法 布立-培絡雷射，VCSELS，VECSELS以及任何其他型式之外/部 空腔雷射。 ° 參考圖1’雷射(例如，職雷射）10光學地耦合至非線性 光學材料構成之光線波長轉換裝置40。由半導體雷射1〇發 〇 射之波長λ 0的輸入光學訊號可直接地輕合至波長轉換裝x 置40或可耦合通過準直以及聚焦之光學元件2〇 %或一些 其他型式射之絲元件絲學祕。波長轉換裝置4〇 ς 半導體雷射hi發射出之輸人光學訊號波長λ G轉換為較高 譜波。該型式構造特別地有用於由較長波長半導體雷射產 生較短波長雷射光束以及能夠使用來作為例如雷射投射系 統之可見雷射光源。輸入光學訊號λ 0可包含例如可見光， 紅外線，近-紅外線以及紫外線之波長。 ， 波長轉換裝置40顯示於圖i中為非線性SHG晶體。波長 201008067 又。以及鮮ω。之輸人絲峨私奸娜裝置 面40以及沿著光學路徑麵輸出面傳播 ^ 之光學路徑為光_康在由“ 表= 皮導_ 由波長轉換編c之輪出光學则 半導=Γ:及=奐裝置40之波長轉換效率決定於 +導體雷㈣以及波長轉錄置4G間 e ;轉換裝S4Q+A生料财級讀㈣_著地下t 虽雷射10之輸出波長偏離波長轉換裝置4G之波 寬度。在包含雷射10例如DBR光源麵以及p_體作為 波長職裝置40作_率加倍應财需要統並不得*、'、 反射以及向_合至雷射1G之雷射二極體。外部空腔回授 能夠使雷射10波長變為非常不敎。波長轉換裝置4〇 換效率對波錢化轉常錄性从㈣向後反射形式 之回授使鮮加倍的轉產生晴的變動。額外地，在例 如雷射投射系統中非線性頻率加倍之應用中需要最高可 能功率之雷射二極體例如為數百毫瓦以達成充份的轉換效 率。 如上述所說明，波長轉換裝置4〇内布拉格_類似光拇會 促使顯著的回授至雷射10。這些布拉格—類似光栅由波長 轉換裝置40之折射率及極化所導致。其中删或懸雷射1〇 使用來系運波長轉換裝置4〇,雷射二極體本身包含布拉格 光柵。在該情況中，波長轉換裝置4〇並不刻意地包含布拉 格光柵。不過，SHG以及其他類似的晶體具有本質性以及不 201008067 想要布拉格光柵，其由於極化處理過程所致。例如，局部應 力在極化處理過程中會加入至波長轉換裝置4〇，其會導致 折射率之變化。額外地，由極化處理過程所產生之任何殘 餘電壓會使極化以及非極化之區域產生不同的折射率。晶 體非-完美局部魅會在結射產錄射^。這些週期 性散射結構會產生共振類似於折射率變化布拉格光柵。在 波長轉換裝置40内雜格料致㈣向後反射以及在 ❹ 雷射10中產生不穩定性。 _圖2以及3顯示出向後反射對雷射穩定性之衝擊。圖2 顯不出在-波長下光源波長為雷射1()增益區段中電流之函 數(約1060nm)，其中並無顯著的布拉格共振。對應於第一· 雷射二極體封裝之實線議，同時對應於第二雷射二極體封 裝之f線1(U。雷射之波長保持為相當地穩定雖然波長並 不隨著雷射模跳躍相關之突然變動而逐漸的增加。另外一 方面，圖3顯示出第一雷射封裝1〇2以及第二雷射封装⑽之 瘳光源波長的範例，其中存在顯著的布拉格共振(约為刪服 如圖3中所示’兩個雷射二極體封裝經歷顯著不穩定性 .其來自波長轉換裝置40之向後反射所致其由於在相位相 匹配波長下布拉格共振所致。因而，為了避免向後反 射，波長轉換裝置40應該加以設計以及製造其方式為在相 位相匹配波長λφ下布拉格共振並不會發生，或顯著地最 小化。 如上述所說明，本發明之特別實施例—般係關於製造 波長轉換裝置40以由波長轉換裝置4〇至半導體雷射1〇之向 201008067 後反射最小化。更特別地，我們瞭解改變或破壞波長轉換 裝置40之相位相匹配波長λ Φ的理想的極化週期Λ ι將碟 保布拉格共振曲線改變或最小化於雷射相位相匹配波長λφ 情況下。因而，由波長轉換裝置4〇向後反射至雷射1〇將顯 著地最小化。 依據本發明一些實施例，應該辨識所需要之相位相匹 配波長λΦ。如上述所說明，相位相匹配波長；1〇為雷射發 〇 射之訊號的泵運波長’在該波長下波長轉換裝置以最大轉 - 換效率轉換訊號之頻率。因為當光線傳播通過波長轉換裝 置時非線性光學材料在輸入波長（即基本波長)以及轉換 波長（即，第一諧波波長）下具有些微不同的折射率，輸入以 及轉換波長變成為異相，如上述所說明。·兩個波長破壞性 地干涉，因而非常少轉換光線由波長轉換裝置輸出。不過 ，輸出訊號在理想的極化週期Λ i下可藉由加入SHG晶體（ 例如PPLN)多個相位-偏移範圍而顯著地增加強度。 ® 在理想的極化週期人!下，傳播通過波長轉換裝置之光 線相位倒置180度於發生任何破壞性干涉之前，使得當光線 -運行波長轉換裝置之長度時只有建設性干涉存在以及轉換 波長之強度建立。相位相匹配波長λφ之理想的極化週期 Λι可由下列公式決定出： 其中： Λ!為極化非線性光學材料之抗_向後反射性週期性， 為極化非線性光學材料轉換頻率之有效折射率， 201008067 以及 cu為極化非線性光學材料輸入頻率之有效折射率。 再次參考圖1，實施例會破壞布拉格共振以及顯著地減 少波長轉換裝置40發出向後反射，其係藉由不規則地變化 波導區域内依序地定位之極化領域之領域寬度而非在上述 決定出理想的極化週期人!下極化晶體達成。不規則地變 化領域寬度亦可說明為不規則噪訊，其加入至極化領域之 〇 位置上。藉由不規則地變化領域寬度，非線性光學材料為 或變為些微地非-週期性，或準_週期性，同時仍然保持週期 性，其有效地使輸入訊號之頻率加倍。布拉格共振因而以 該方式在極化波長轉換裝置中減少或消除，因為波導區域 不非真正較長之週期。因而，在相位相匹配波長又①下向 後反射顯著地減少以及雷射10保持穩定。在波長轉換裝置 4〇中領域之寬度顯示於圖i中為了顯示用途該圖被放大， 藉由理想的極化週期Λι加上或減去分裂值改變寬度。分 © ^值應馳著地小於理㈣極化聊Λι。分裂值太大將 二響由基本波長轉換域率加倍的波長之轉換效率，其將 'ϋ或凡全地破壞第二''諧波光線之產生。因而，應該選擇 分裂雜得減纽㈣難置40之布祕魏以及相對應 光線之向後反射，同時亦保持波長轉換裝置之轉換效率 為或近最大效率。理想的極化領域46具有之領域寬度由理 ί的極化週齡1蚊出，同時大_域47為大於理想的領 ’ 46達刀裂值，以及小的領域48為小於理想領域仙達分裂 值項域46 48可沿著波導區域之長度改變以達成轉換效 201008067 率最尚值，以及應該平均理想的極化週期Λι。 圖4為對數曲線圖，其顯示出兩個極化ppLN晶體相對於 輸入波長之布拉格共振。曲線107為為在理想的極化週期 八!下極化之晶體的布拉格共振以及曲線1〇8為利用不規則 地變化領域寬度極化之範例性波長轉換裝置4〇的布拉格共 振。在所顯示範例中，理想的極化週期八!為3. 3微米以及 分裂值為0.1微米。因而，曲線108之範例性波長轉換裝置 ❹40極化具有領域為以3· 2, 3. 3以及3. 5微米寬度不規則地變 化而異於理想的極化週期3. 3微米。如曲線圖可看到 ，在理想的極化週期Λ!下極化之波長轉換裝置的週期性領 域導致之布拉格共振為顯著地大於範例性波長轉換裝置4〇 之布拉格共振。〇.丨微米分裂值相當大足以改變週期以消 除由布拉格共振所產生之向後反射，但是相當小並不會顯 著地影響晶體之轉換效率，即範例性波長轉換裝置具有轉 換效率，其保持接近在理想的極化週期極化之晶體的 φ 最大轉換效率。 其他實施例可藉由加入小的不連續或不連續性至波導 _區域内一個或多個非-理想的極化領域減少由波長轉換裝 置40向後反射至雷射1〇。在極化區域之位置上小至〇 1微 '米之變化或不連續性對布拉格共振具有顯著影響。不連續 提供由第二一半波導反射之光線相位與第一一半波導反射 之光線的相位相反。為了確保向後—反射光線被偏移一半 波長，應該考慮向前以及向後傳播。因而，相位偏移應該約 為四分之一波。施加於非-理想的極化領域之不連續寬^队 13 201008067 定義為:201008067 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention generally relates to a wavelength conversion device and a method of fabricating the same. More particularly, embodiments of the present invention are directed to wavelength conversion devices and methods of fabricating the same that enable the secreting cycle operation to refrain from less Bragg resonance and back reflection of associated light while maintaining efficient conversion efficiency of the wavelength conversion device. - [Prior Art] - A wavelength conversion device comprising a periodically polarized nonlinear optical material such as lithium niobate may be configured to double the laser to the input signal frequency, which is borrowed by periodically inverting the range within the nonlinear optical material It is achieved by using a quasi-phase match. However, these periodically inverted ranges produce unwanted Bragg resonances at the phase matching wavelengths of the polarized nonlinear optical material (i.e., the wavelength conversion device doubles the frequency of the input signal at maximum efficiency at the input signal wavelength). It promotes the unwanted back-projection of the laser from the wavelength conversion device to the laser, which negatively affects the stability of the laser when reflection occurs in the fundamental wavelength. Additionally, if the Bragg resonance occurs within a wavelength that doubles the frequency, the Bragg resonance can cause the transmit power to drop significantly. Embodiments of the present invention improve the stability of the laser by reducing the period of polarization of the periodically polarized nonlinear optical material by reducing the retroreflection to the laser to destroy the Bragg resonance caused by the polarization domain. SUMMARY OF THE INVENTION In accordance with an embodiment of the present invention, a method of fabricating a wavelength conversion device is provided that includes a nonlinear optical material having an input face, an output face, and a 201008067 waveguide region extending from the input face to the output face. According to this method, the wavelength conversion f is produced by the polarization period of the wavelength-matching device and the phase-matching wavelength of the wavelength conversion device. The planar optical material is polarized by the region of the induced waveguide region, which includes the irregularly varying domain width, and the f width is defined by the ideal polarization period Λ f plus the money to the branch. Bragg resonance and the chopping of the field width polarization by the unchanging ground, the retroreflection of the light emitted by the conversion device to the laser is at least less than one-order Bragg resonance and nonlinear optics polarized with an ideal polarization period Λι Material_back reflection. Irregularly varying the width of the field is polarized by the wavelength conversion device. The conversion efficiency is at least one-half the maximum conversion efficiency. According to another embodiment of the present invention, there is provided a method of fabricating a wavelength conversion device comprising a nonlinear optical material having an input face, an output face and a waveguide region extending from the input face. According to this method, the wave length conversion means is manufactured by recognizing the phase matching wavelength of the wavelength conversion means and determining the ideal polarization period 匹配 of the phase matching wavelength h of the wavelength conversion means. A nonlinear optical material is polarized by initiating a waveguide region for a plurality of sequentially positioned regions comprising a plurality of ideal polarization domains and one or more non-ideal polarization domains, wherein the non-ideal polarization domain comprises From the ideal polarization period of eight! Add or subtract from the value of the boundary and the ideal polarization domain contains the ideal polarization period ~ defined width. Selecting a discontinuity value such that the phase of the reflected light from the second-half waveguide region is opposite to the phase of the light reflected by the first-half waveguide region 201008067 to polarize the conversion efficiency of the input signal having the non-ideal polarization domain by the wavelength conversion device At least one and a half of the maximum conversion efficiency. According to another embodiment of the present invention, a wavelength conversion device is provided. More particularly, in accordance with an embodiment of the present invention, a wavelength conversion device includes a nonlinear optical material having an input face, an output face, and a waveguide region extending from the input face to the output face. The waveguide region further includes a plurality of sequentially positioned regions having a width defined by an ideal polarization period Λ, plus or minus a split value, which varies irregularly. Less than the ideal polarization period of eight, the split-value makes the Bragg resonance and the backward reflection of the corresponding ray at least smaller than the Bragg reflection of the polarized light of the nonlinear optical material in the ideal polarization period. The split value also allows the input signal having an irregularly varying domain width to be converted by the wavelength conversion device to at least half the maximum efficiency of the nonlinear optical material polarized with an ideal polarization period Λι. In accordance with another embodiment of the present invention, a wavelength conversion device is provided that includes a nonlinear optical material having an input face, an output face, and a waveguide region extending from the input face to the output face. More particularly, the waveguide & field according to one embodiment comprises a plurality of ideal polarization domains and one or more non-ideal. polarization domains. The non-ideal polarization domain contains the width defined by the ideal polarization period 加上 plus or minus the discontinuity value, which is less than the ideal polarization period ΛI, and the ideal polarization domain contains the ideal polarization period. Eight, define the width. [Embodiment] The present invention relates generally to semiconductor laser and wavelength conversion devices, such as a second harmonic generation crystal (SHG), which can be configured in different ways. Example 5 201008067 As and by way of example and without limitation, a short-wavelength light source can be configured to be modulated at high speed by dispersing a single-wavelength semiconductor laser, such as a distributed feedback (DFB) laser, to spread the Bragg Reflector (j)BR) laser, vertical cavity surface _ emission laser (VCSEL), vertical external cavity surface-launching laser (vecsEL) or Fabry-pey laser and light wavelength conversion device such as SHG crystal Consolidated to achieve. As is familiar to those familiar with laser design, DFB lasers are resonant-cavity lasers, which use squares or etched into semiconductor materials as reflective media-like structures. (10) The R laser is a laser that is actually separated by a semiconductor laser electronic pumping area. On the other hand, the Fabry-Peel laser does not have a wavelength selective section and thus produces a plurality of wavelengths. In order to operate the Fabry-Perot laser in a single mode state, it is therefore necessary to add a wavelength selective component to the optical path to reflect some of the light towards the diode and to stabilize the wavelength. This power b can be achieved by integrating the Bragg light in the SHG crystal waveguide portion. These and other types of lasers have been considered for use in accordance with the present invention.波长 The wavelength conversion device can comprise an SHG crystal. Although the SHG crystal produces an output signal that has twice the frequency of the original or input optical signal, these _ signals become out of phase with each other. When the light travels in the waveguide region, the substantially (ie, input) and the second-harmonic wavelengths become out of phase, such that the second-harmonic signal is generated close to the input surface of the wavelength conversion device. The second-harmonic light signal at the output surface of the wavelength conversion device is out of phase. This results in a very small amount of second-harmonic light. In order to obtain a constructive phase match between the second-harmonic light signals generated in the wavelength conversion device, quasi-phase matching is employed. The quasi-phase matching can be achieved by periodically inverting the polarization field of 201008067 in the hybrid material. The polarization consists of inverting the orientation of the crystal axis of the wavelength conversion device to ensure both infrared and visible light. Wei Changjian device read Lai Wen. Final phase correction can be achieved by adding a phase offset to each field. Non-linear optical materials suitable as SHG steroids may include non-limiting periodic polarization of sharp acid (PPU), lion's polarization recording (ppLT), and periodic polarization of deoxygenated phosphate (10) TP ). Polarized cocoa is introduced into the wavelength conversion device by a number of processes, including, for example, an electron beam sweeping cat, applying an electric field, or crystal growth. The wavelength conversion device can generate a higher harmonic of the basic laser signal by adjusting, for example, a biliary DBR or a brain laser to the center of the spectrum of the wavelength conversion device, which shifts the wavelength to 530 nm. However, in this higher harmonic generation system, the important parameter is the stability diode of the wavelength laser. For example, the wavelength conversion efficiency of a wavelength conversion device doped with Mg pp PNL is strongly determined by the matching between the wavelengths of the laser diode and the wavelength conversion device. The conversion of the wavelength conversion device 10 is a function of a very narrow wavelength, such that any wavelength instability produces a frequency doubling of the intensity fluctuations of the light. We have learned that retroreflection by wavelength conversion devices and re-injection into semiconductor lasers play a key role in wavelength stability. Lasers such as the dbr laser are very sensitive to feedback and the feedback value is as low as -60 to _7 〇 dB, which makes the wavelength unstable. For example, Bragg gratings can cause retroreflection in a laser system. We have also learned that although wavelength converting devices such as periodically polarized SHG crystals cannot deliberately contain induced Bragg gratings in the [] or dfb laser systems, bulk SHG crystals have some periodic or near-periodic periodicity. For example, crystal polarization or other crystal waveguide formation related characteristics. These characteristics are similar to the unwanted Bragg grating and the significant feedback to the laser diode. These Bragg reflections can produce laser instability when occurring at a fundamental wavelength and/or when power drops at a wavelength at which the frequency doubles. For the challenges of wavelength matching and stability related in the development of semiconductor laser sources, embodiments of the present invention relate to wavelength conversion devices and methods for their manufacture to reduce the backward reflection from a wavelength viewing device to a rotating body to a low Therefore, the stability of the semiconductor laser wavelength is improved. Although the inventive concept is primarily directed to laser content, it has been contemplated that the control modes described herein are also used in various types of semiconductor lasers, including the non-limiting Dfb laser method, the Buley-Peel laser, VCSELS, VECSELS. As well as any other type of cavity laser. The light source wavelength conversion device 40 constructed of a non-linear optical material is optically coupled to a laser (e.g., a laser) 10 with reference to FIG. The input optical signal of the wavelength λ 0 emitted by the semiconductor laser 1 can be directly coupled to the wavelength conversion device 40 or can be coupled through the collimating and focusing optical element 2% or some other type of wire. The components are secret. The wavelength conversion device 4 ς semiconductor laser light hi emits the input optical signal wavelength λ G converted into a higher spectral wave. This type of construction is particularly useful for producing shorter wavelength laser beams from longer wavelength semiconductor lasers and as visible laser sources that can be used, for example, as laser projection systems. The input optical signal λ 0 may include wavelengths such as visible light, infrared light, near-infrared light, and ultraviolet light. The wavelength conversion device 40 is shown in Figure i as a nonlinear SHG crystal. Wavelength 201008067 Again. And fresh ω. The optical path of the input of the human body and the surface of the optical path is 40. The light path is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ : and = 奂 device 40 wavelength conversion efficiency is determined by + conductor Ray (four) and wavelength transcription between 4G e; conversion S4Q + A raw material financial reading (four) _ underground t although the output wavelength of laser 10 deviates from the wavelength conversion device 4G wave width. Including laser 10, such as DBR source surface and p_ body as wavelength device 40, _ rate doubles the need for integration, not *, ', reflection and _ to laser 1G laser 2 Polar body. The external cavity feedback can make the laser 10 wavelength become very unsatisfactory. The conversion efficiency of the wavelength conversion device 4 is changed from the (four) retroreflective form to the reciprocal reflection form. In addition, in applications where nonlinear frequency doubling in, for example, a laser projection system, the highest possible power of the laser diode is required, for example, several hundred milliwatts to achieve sufficient conversion efficiency. As explained above, the wavelength The conversion device 4 布拉格 Prague _ similar to the light thumb will promote significant Granted to the laser 10. These Bragg-like gratings are caused by the refractive index and polarization of the wavelength conversion device 40. The laser or the laser is used to charge the wavelength conversion device 4, and the laser diode itself contains Bragg grating. In this case, the wavelength conversion device 4 does not intentionally contain a Bragg grating. However, SHG and other similar crystals are essential and do not have a 201008067 wanted Bragg grating due to the polarization processing process. The local stress is added to the wavelength conversion device 4 during the polarization process, which causes a change in the refractive index. Additionally, any residual voltage generated by the polarization process causes polarization and non-polarization regions. Producing different refractive indices. Crystal non-perfect local fascination will be recorded in the junction. These periodic scattering structures will produce a resonance similar to the refractive index change Bragg grating. In the wavelength conversion device 40, the (4) retroreflection And instability in the ❹ laser 10. _ Figures 2 and 3 show the impact of retroreflection on the stability of the laser. Figure 2 shows no-wavelength The wavelength of the light source is a function of the current in the laser 1 () gain section (about 1060 nm), where there is no significant Bragg resonance. Corresponding to the solid line of the first · laser diode package, corresponding to the second mine The f-line 1 of the diode package (U. The wavelength of the laser remains fairly constant, although the wavelength does not increase gradually with sudden changes in the laser mode jump. On the other hand, Figure 3 shows the first An example of the wavelength of the xenon source of the laser package 1〇2 and the second laser package (10), where there is significant Bragg resonance (approximately as shown in Figure 3). Two laser diode packages experience significant instability It is caused by the backward reflection of the wavelength conversion device 40 due to Bragg resonance at the phase matching wavelength. Therefore, in order to avoid backward reflection, the wavelength conversion device 40 should be designed and manufactured in such a manner as to match the wavelength at the phase. The Bragg resonance at λφ does not occur, or is significantly minimized. As explained above, the particular embodiment of the present invention generally relates to the fabrication of the wavelength conversion device 40 to minimize reflection from the wavelength conversion device 4 to the semiconductor laser. More specifically, we understand that changing or destroying the phase of the wavelength conversion device 40 to match the ideal polarization period of the wavelength λ Φ ι changes or minimizes the dish Bragg resonance curve to the laser phase matching wavelength λφ. Thus, the back reflection from the wavelength conversion device 4 to the laser 1 显 will be significantly minimized. In accordance with some embodiments of the present invention, the desired phase matching wavelength λ Φ should be identified. As explained above, the phase matches the wavelength; 1 〇 is the pumping wavelength of the signal emitted by the laser ray at which the wavelength converting device converts the frequency of the signal with maximum conversion-change efficiency. Because the nonlinear optical material has a slightly different refractive index at the input wavelength (ie, the fundamental wavelength) and the converted wavelength (ie, the first harmonic wavelength) as the light propagates through the wavelength conversion device, the input and conversion wavelengths become out of phase, such as As explained above. • The two wavelengths destructively interfere, so that very little converted light is output by the wavelength conversion device. However, the output signal can significantly increase the intensity by adding multiple phase-offset ranges of the SHG crystal (e.g., PPLN) under the ideal polarization period Λ i . ® Under the ideal polarization period, the phase of the light propagating through the wavelength conversion device is inverted 180 degrees before any destructive interference occurs, so that when the light-runs the length of the wavelength conversion device, only constructive interference exists and the wavelength is converted. Strength is established. The ideal polarization period 相位ι of the phase matching wavelength λφ can be determined by the following formula: where: Λ! is the anti-backward reflective periodicity of the polarization nonlinear optical material, which is the effective refraction of the polarization nonlinear optical material switching frequency. Rate, 201008067 and cu are the effective refractive indices of the input frequencies of polarized nonlinear optical materials. Referring again to FIG. 1, the embodiment will destroy the Bragg resonance and significantly reduce the backward reflection of the wavelength conversion device 40 by irregularly varying the width of the field of the polarization domain sequentially located within the waveguide region rather than determining the above. The ideal polarization period is achieved! The lower polarization crystal is achieved. Irregularly varying the width of the field can also be described as irregular noise, which is added to the 〇 position of the polarization domain. By irregularly varying the width of the field, the nonlinear optical material becomes either slightly non-periodic, or quasi-periodic, while still maintaining periodicity, effectively doubling the frequency of the input signal. The Bragg resonance is thus reduced or eliminated in this manner in the polarization wavelength conversion device because the waveguide region is not a truly long period. Thus, the backward reflection is significantly reduced and the laser 10 remains stable at a phase matching wavelength of one. The width of the field in the wavelength conversion device 4 is shown in Figure i. The figure is enlarged for display purposes, and the width is changed by adding or subtracting the split value by the ideal polarization period. Points © ^ value should be less than the rational (four) polarization chat. A split value that is too large will be the conversion efficiency of the wavelength doubled by the fundamental wavelength conversion domain rate, which will destroy the generation of the second ''harmonic light'. Therefore, it should be chosen to split the miscellaneous (4) difficult to set 40 and the backward reflection of the corresponding light, while also maintaining the conversion efficiency of the wavelength conversion device at or near maximum efficiency. The ideal polarization field 46 has a field width that is determined by the polarization of the age of 1 mosquito, while the large _ domain 47 is larger than the ideal collar '46 knife crack value, and the small field 48 is smaller than the ideal field. The value term field 46 48 can be varied along the length of the waveguide region to achieve a conversion efficiency 201008067 rate most desirable value, and should average the desired polarization period Λι. Figure 4 is a logarithmic plot showing the Bragg resonance of two polarized ppLN crystals relative to the input wavelength. The curve 107 is the Bragg resonance of the crystal polarized at the ideal polarization period -8 and the curve 1 〇 8 is the Bragg resonance of the exemplary wavelength conversion device 4 利用 which irregularly changes the domain width polarization. In the example shown, the ideal polarization period is eight! 3. 3 microns and the split value is 0.1 microns. 5微米。 Thus, the exemplary wavelength conversion device 曲线40 of the curve 108 has a field having a width of 3. 2, 3. 3 and 3.5 microns irregularly varying from the ideal polarization period of 3. 3 microns. As can be seen from the graph, the Bragg resonance in the periodic domain of the wavelength conversion device under the ideal polarization period Λ! is significantly greater than the Bragg resonance of the exemplary wavelength conversion device 4〇. The 丨.丨 micron split value is quite large enough to change the period to eliminate the retroreflection caused by Bragg resonance, but is quite small and does not significantly affect the conversion efficiency of the crystal, ie the exemplary wavelength conversion device has conversion efficiency, which remains close to The maximum φ maximum conversion efficiency of an ideal polarization-polarized crystal. Other embodiments may reduce back reflection from the wavelength conversion device 40 to the laser 1 by adding small discontinuities or discontinuities to one or more non-ideal polarization domains within the waveguide region. Variations or discontinuities in the position of the polarization region as small as 〇 1 μm change have a significant effect on Bragg resonance. The phase of the light reflected by the second half of the waveguide is opposite to the phase of the light reflected by the first half of the waveguide. To ensure that the backward-reflected light is offset by half the wavelength, forward and backward propagation should be considered. Therefore, the phase shift should be approximately a quarter wave. Discontinuous width applied to the non-ideal polarization domain 13 201008067 Defined as:
η 其中： λ br為向後反射光線之波長， k為整數，以及 7?為非線性光學材料之折射率。η where: λ br is the wavelength of the retroreflected light, k is an integer, and 7 is the refractive index of the nonlinear optical material.
顯示於圖5中實施例包含多個理想的極化領域46，其具 有領域寬度等於如上述所定義之理想極化週期ΛΙ，以及一 個非-理想的極化領域50具有寬度等於理想的極化週期八1 加上不連續值。雖細5顯示出只有—個非_理想的極化領 域，實施例可包含一個或多個非—理想的極化領域以及由 理想的極化週期八^咸去不連續值界定出之寬度。 作為-項範例，日日日體折射率η為2. 2以及考慮光線在波 長轉換裝置4G _來回撕，具林連·值為丨微米之 非-理想的極化領獻絲路徑長度增加G. 44微米其在輸 入訊號為1. 062微米下為接近半波。因而極化位置非常小 的變化將會使建設性干涉轉變為破壞性干涉以及因而在相 位相匹配錄λ φ下相魏改變雜祕振之形狀，該位 置使向後反射紐相位偏移向後反射親之波長一半。額 外地，只要施加於非-理想的極化領域或領域之不連續性值 保持遠小於極化週期本身（即，至少—個數量級)，非—理想 的極化領域對晶體讎效率轉影響具有非常小影響。 =6顯示出曲線，其描繪出相對於輸入波長之8麵長晶 體的布拉格共振。曲線104為在波長轉餘置40之波導區 14 201008067 域内連續地職性光柵的雜格共振，同時曲線106為波長 轉換裝置之布拉格共振該裝置包含非理想的極化領域， 其大於理想的極化週期Λι 〇122微米。當波導為某一折 射率時，邊不連續相當於波長四分之一。如曲線圖可看到， 曲線104之布拉格共振在相位相匹配波長下具有大的尖峰， 其促使顯著的以及破壞向後反射至雷射1〇。不過，利用接 近波導區域巾央之非_理想雜化職_極化區域達The embodiment shown in Figure 5 includes a plurality of ideal polarization domains 46 having a domain width equal to the ideal polarization period 如 as defined above, and a non-ideal polarization domain 50 having a width equal to the ideal polarization. Cycle VIII plus the discontinuity value. Although the thin 5 shows only a non-ideal polarization domain, the embodiment may include one or more non-ideal polarization domains and a width defined by the ideal polarization period. As an example, the daily refractive index η of the solar field is 2.2 and that the light is torn back and forth in the wavelength conversion device 4G _, and the non-ideal polarization of the wavelength of the lining is increased. 44 microns is nearly half-wave at an input signal of 1.062 microns. Therefore, a very small change in the polarization position will cause the constructive interference to transform into destructive interference and thus change the shape of the miscellaneous vibration in the phase matching λ φ, which makes the retroreflective phase shift backwards. Half the wavelength. Additionally, as long as the discontinuity value applied to the non-ideal polarization domain or domain remains much less than the polarization period itself (ie, at least an order of magnitude), the non-ideal polarization domain has an effect on the crystal enthalpy efficiency. Very small impact. =6 shows a curve depicting the Bragg resonance of an 8-sided crystal with respect to the input wavelength. Curve 104 is the lattice resonance of the continuous-volume grating in the region of the waveguide region 14 201008067 of the wavelength-shifting 40, while the curve 106 is the Bragg resonance of the wavelength conversion device. The device contains a non-ideal polarization domain, which is larger than the ideal pole. The cycle is Λι 〇 122 microns. When the waveguide is at a certain refractive index, the edge discontinuity corresponds to a quarter of the wavelength. As can be seen from the graph, the Bragg resonance of curve 104 has a large peak at the phase matching wavelength, which promotes significant and destructive retroreflection to the laser. However, the use of the near-waveguide area is the non-ideal hybrid position
0· 122促使在曲、線106中央處相位翻轉。雖然範例性波長轉 換裝置40包含非-理想的極化領域於在波導區域中央處，一 個或多個非-理想的極化領域可位於波導區域内任何放置 處，只要雜格共振減為最低。存錢移向後反射光線之 相位達波長—半之不連續在相位她配波長；U下實質上 減少向後反射至雷射。 —作為說明以及界定本發_途，人們了解在此所使用" 顯著地”以及”實質上"代表可能歸因於任何量化比較值 測量，或其他絲法的財不確定性。”大體上"―詞在這 裡也用來代表在不改變所討論主題之基本功能的前提下， 量化表示法可以跟陳述參考值不同的程度。 ， 人們瞭解本發明先前詳細說明預期提供概念或架構 為了解申請專利範圍所界定出本發明之原理以及特徵。業 界熟知此麟者_本發咐_特多奴變而、 會脫離本發明讀私細。_本㈣錢本發明各種 變化及改變，其麟下列申請專利麵朗麵範圍内。 要注意，這裡陳述將本發明的元件以特定方式來 15 201008067 步驟實施，，，或”配置"來包含狀靴或則权方式來作 用，适些都是結構上的陳述，而不是用途上的陳述。具體地 說’這裡所提到元件"配置"的方式是指出此元件現有的實 體狀況j此麟視為此元件之結構躲_確陳述。 在詳、、田描述本發明並參考特殊實施例之後，我們可以 ，白看出修改和_是可能的，但是都不脫_加主張所 定，之本發明的範圍。具體的說，雖然本發日⑽一些方面 在這裡被標識驗好，_有利，或令人的，但是本發 明不-定要祕在本發明這她好的方面。 【圖式簡單說明】 下列本發明歡實關之詳細綱當連同下列附圖閱 ，時將月b 地瞭解，其中相同的結構以相同的參考符 ^虎說明。 圖1不意性地顯示出依據本發明一個或多個實施例之 DBR或類似型式半導體雷射光學地輕合至光線波長轉換裝 置。 圖2以及3顯示出發射波長之演變，為DBR f射中增益 流之函數。 、圖4為曲_，其顯示出依據本發明—個或多個實施例 波長轉換裝置之布減共振曲線。 圖5示意性地顯示出依據本發明一個或多個實施例之 波長轉換裝置。 、圖6為曲線圖’其顯示出依據本發明一個或多個實施例 波長轉換農置之布祕共振曲線。 201008067 【主要元件符號說明】 雷射10;光學元件20, 30;波長轉換裝置40;領域46 ,47, 48;非-理想的極化領域50。 ❹ 170·122 causes the phase to be inverted at the center of the curve and line 106. While the exemplary wavelength conversion device 40 includes a non-ideal polarization domain at the center of the waveguide region, one or more non-ideal polarization domains can be located anywhere in the waveguide region as long as the alias resonance is minimized. The money moves toward the rear to reflect the phase of the light to a wavelength—half of the discontinuity is in phase with the wavelength; U is substantially less back-reflected to the laser. - As an illustration and definition of this issue, it is understood that the use of "significantly" and "substantially" as used herein may be attributed to any quantified comparative value measurement, or other monetary uncertainty. The "substantially" word is also used herein to mean that the quantitative representation may differ from the stated reference value without changing the basic function of the subject matter in question. It is understood that the foregoing detailed description of the invention is intended to provide a concept or The architecture defines the principles and features of the present invention in order to understand the scope of the patent application. The industry is well aware of this lining_本本咐_特多奴变, and will leave the invention to read the private details. _ Ben (4) Money The invention changes and changes The following patents are within the scope of the patent application. It is noted that the elements of the present invention are stated in a specific manner to the implementation of the steps of 2010 20100,67, or "configuration" to include the boots or the right way to function. These are structural statements, not statements of purpose. Specifically, the means of "configuration" referred to herein is to indicate the actual state of the component. This is considered to be a structural statement of this component. Having described the invention in detail, and after referring to the specific embodiments, we can see that modifications and _ are possible, but are not intended to limit the scope of the invention. Specifically, although some aspects of this publication (10) are identified here, _ advantageous, or convincing, the present invention is not intended to be a good aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The following detailed description of the present invention will be understood in conjunction with the following drawings, wherein the same structure is illustrated by the same reference character. 1 unintentionally shows a DBR or similar type semiconductor laser optically coupled to a light wavelength conversion device in accordance with one or more embodiments of the present invention. Figures 2 and 3 show the evolution of the emission wavelength as a function of the gain flow in the DBR f shot. Figure 4 is a curved diagram showing the relief resonance curve of a wavelength conversion device in accordance with one or more embodiments of the present invention. Fig. 5 schematically shows a wavelength conversion device in accordance with one or more embodiments of the present invention. Figure 6 is a graph showing the resonance curve of a wavelength-converted farm in accordance with one or more embodiments of the present invention. 201008067 [Description of main component symbols] Laser 10; optical components 20, 30; wavelength conversion device 40; field 46, 47, 48; non-ideal polarization domain 50. ❹ 17